1. Field of the Invention
The present invention concerns a method of producing partially crosslinked rubber-resin composition. More particularly, it concerns the method of producing the partially crosslinked rubber-resin composition comprising dynamically heat treating a peroxide-curable olefin copolymer rubber and a peroxide-decomposing polyolefin resin in the presence of an organic peroxide.
2. State of the Art
Various methods are used in production of partially crosslinked rubber-resin composition comprising a partially crosslinked peroxide-curable olefin copolymer rubber and a polyolefin resin. As the olefin copolymer rubber, ethylene/propylene copolymer rubber and ethylene/propylene/non conjugated polyene copolymer rubber are typical. The method which comprises melting and kneading the copolymer rubber with an organic peroxide in a Banbury mixer as the dynamic heat treatment for the partial crosslinking followed by mixing with a polyolefin resin, and the method which comprises melting and kneading the copolymer rubber with an organic peroxide in a Banbury mixer in the presence of a peroxide-decomposing polyolefin resin such as polypropylene are batchwise process, and therefore, not economical way of production. Further, in the former it is difficult to obtain the product of constant quality because of insufficient mixing of the partially crosslinked rubber and the polyolefin resin.
In order to obtain the partially crosslinked rubber-resin composition having constant quality given by homogeneous mixing of the partially crosslinked copolymer rubber and the polyolefin resin, it is preferable to preliminarily melt and mix the copolymer rubber and the peroxide-decomposing polyolefin resin such as polypropylene to form particle, and then, to melt and knead the particle with an organic peroxide in an extruder for the dynamic heat treatment. This method is also not advantageous because of necessity of the preliminary step of melting and mixing the copolymer rubber and the polyolefin resin.
Thus, there has been demand for the method of melting and kneading the copolymer rubber and the peroxide-decomposing polyolefin resin in the presence of an organic peroxide for the dynamic heat treatment which is carried out continuously.